PROJECT SUMMARY Methamphetamine (MA) causes devastating harm to individuals, yet there are no approved treatments for MA use disorders. Female MA users have increased rates of depression, and more severe depressive symptoms than males. Depression may contribute to the risk of relapse because negative mood is associated MA craving. Our previous neuroimaging study found that female MA users have decreased frontal lobe phosphocreatine (PCr) levels, compared with both male MA users and female healthy controls. Following up on this key translational finding, preliminary data collected at our site suggests that when administered to female MA users, creatine monohydrate supplementation is associated with increased brain PCr, N-acetyl aspartate (NAA, a marker for neuronal health) and gamma-aminobutyric acid (GABA, the major inhibitory neurotransmitter of the brain). PCr is the substrate reservoir for the creatine kinase reaction, which reversibly converts PCr into adenosine triphosphate (ATP), the brain's major energy supply, and creatine. Clinically, creatine administration was associated with decreased depression and anxiety symptoms. It may also reduce MA use, measured by urine drug screens. This proposal follows expert recommendations to target cognitive enhancement, and neuronal repair, in developing pharmacotherapies for stimulant addiction. The long-term goal of this research program is to define the alterations in brain chemistry that underlie MA use disorders, and to utilize translational MRS neuroimaging to identify rational brain-based treatment targets. Once a hypothesis- driven intervention is identified, MRS can then be further employed in treatment studies, to verify that target engagement is achieved. In women with MA use disorders, creatine is a hypothesis-generated intervention aimed at restoring neurochemistry, reducing depression and anxiety symptoms, and improving cognitive function. Over a 5-year period, the project will enroll 76 women between the ages of 18 and 55 with MA use disorders and randomize them to 8 weeks of treatment with either creatine or placebo. Neuroimaging and cognitive testing of MA users will be performed at baseline, and repeated after 8 weeks of treatment. As outcome measures, multi-level assessments will be performed for brain chemistry, cognitive function, and clinical symptoms. It will be determined in female MA users whether creatine supplementation, compared to placebo, will 1) repair MA- induced neurochemical toxicity in the frontal brain regions, which will be assessed using phosphorus-31 and proton-1 multinuclear magnetic resonance spectroscopy (MRS), 2) improve depression and anxiety, which will be assessed using Hamilton Depression Rating Scale and Beck Anxiety Inventory tests, and 3) restore cognitive deficits associated with MA toxicity, which will be assessed using Wisconsin Card Sorting Task, the Stroop Color-Word Test, and the Wechsler Memory Scale. Additionally, urine drug testing results will be explored to determine the likelihood of reduced MA use following creatine supplementation.